The Chahak intrusive complex is located 58 km southeast of Fariman, south of Chahak Village, in Razavi Khorasan Province, northeastern Iran. This complex comprises intrusive rocks of Late Precambrian (Neoproterozoic) and Paleozoic age. It consists of mafic, intermediate, and felsic (granitoid) rocks. The granitoids encompass a wide range of lithologies, including granodiorite, monzogranite, syenogranite, trondhjemite, and quartz-rich granitoids. The intermediate rocks are predominantly diorite and quartz diorite, whereas the mafic rocks comprise gabbro and hornblende gabbro. Although the Chahak intrusive complex is situated north of the major Doruneh Fault, the emplacement of its intrusive bodies was primarily controlled by independent northwest-southeast-trending fault systems. Owing to their antiquity, the rocks have been affected by chloritic, epidotic, and sericitic alteration. Geochemically, the rocks are classified into medium- to high-K calc-alkaline granitoids, very low-K (Na-rich) granitoids, and subalkaline mafic to intermediate rocks with predominantly tholeiitic affinity. Based on the Aluminum Saturation Index (ASI), the K-rich granitoids are peraluminous to metaluminous, the Na-rich granitoids are peralkaline, and the gabbros are metaluminous. Tectonic discrimination diagrams indicate that the Na-rich granitoids show the closest affinity to oceanic plagiogranites (OP) and plot mainly within the Late-orogenic field on the R1-R2 diagram. In contrast, the K-rich granitoids are predominantly distributed within the post-orogenic granite (POG) field and along the boundary between the Post-orogenic and Syn-collision fields. Furthermore, the gabbros plot within the Ocean Island field on the Pearce (1977) diagram and within the pre-collision, differentiated mantle field on the Batchelor and Bowden (1985) diagram. Collectively, these results indicate that the Chahak intrusive complex records a multi-stage magmatic evolution and preserves evidence of pre-collisional, late-orogenic, and post-orogenic tectonomagmatic events.